Chemical defense strategies of marine organisms.

The diverse habitats of the marine environment and the adaptation required to live either in the open water or attached to a substrate resulted in various defense strategies. This review covers different ways how organisms from the plankton can maintain a chemical defense as well as the dynamic chemical defense strategies of benthic organisms. It opens with a detailed discussion of recent studies of chemical defenses among organisms floating in the open water. These defenses include the production of toxins by harmful algal blooms as well as the rapid production of defensive metabolites from non-toxic precursors upon cell disruption. A comprehensive account of recent advances in the field of dynamic chemical defense strategies of benthic organisms is then presented. It includes the known examples of activated defense based on the enzymatic transformation of storage metabolites as well as induced chemical defense strategies. These strategies depend on the recognition of signals from an herbivore or pathogen, followed by the up-regulation of the biosynthesis of metabolites involved in the chemical defense.